1. Field of the Invention
The present invention relates to how network availability information, including IP Multimedia subsystem registration status, out-of-coverage status, circuit switched attached status or packet switched attached status, is represented as presence information. In particular, the present invention is directed to the format of the network availability status for presence information data format representation.
2. Description of the Related Art
In an IP multimedia subsystem (IMS), a presence service provides the ability for a home network to manage presence information of a user's device, service, or service media, even while roaming. The presence service is a software system whose role is to collect and disseminate presence information, subject to a wide variety of controls. The user's presence information may be obtained through input from the user, information supplied by network entities, or information supplied by elements external to the home network. Currently, there is no solution of how network availability information, including IMS registration status, out-of-coverage status, circuit switched attached status or packet switched attached status, is represented as presence information.